1. Field of the Invention
This invention relates to the magnification changing photo-taking optical system capable of being contained in an electronic still camera or the like.
2. Related Background Art
In a single-lens reflex camera or the like, there is known an auxiliary lens such as a front conversion lens adapted to be mounted forwardly of a photo-taking lens system to vary the focal length or a rear conversion lens adapted to be mounted rearwardly of the photo-taking lens to vary the focal length.
Also in a lens shutter type camera, there is known a two-focus lens in which a rear conversion lens is designed to be capable of being removably mounted rearwardly of a fixed focus lens and accomplishing photographing with the focal length changed.
However, the front conversion lens adapted to be mounted forwardly of the photo-taking lens is relatively large and heavy in itself and therefore the operability of the camera becomes worse, and this is not preferable. Also, both the front conversion lens and the rear conversion lens adapted to be mounted rearwardly of the photo-taking lens need be mounted to the photo-taking lens each time and therefore, they suffer from the problem that it is impossible to effect a magnification change in a moment and the magnification changing operation is cumbersome.
Further, the conventional two-focus lens contained in a camera is preferable for making the camera compact, but can only accomplish photographing at two focal lengths and it has been impossible to change the focal length to more than two kinds.